The present invention is directed to a vent filter with a direct sample capability, more particularly, the present invention is directed to a vent filter with a direct sample capability wherein the vent filter is installed in a container which contains material that may include or generate gasses.
Material contained in containers frequently include or generate gasses or vapors need, for various reasons, to be vented from the container. It is frequently necessary or desirable to have knowledge of what these gasses or vapors are so that decisions can be in made with respect to the material within the container. This is especially the case if the material in the container is hazardous waste which generates or includes gasses which are, for one reason or another, also possibly hazardous. For example, transuranic waste stored in containers such as drums, convenience cans or bags wherein hydrogen gas as well as volatile organic compounds may be generated from the waste. If these gases or vapors are not vented, an explosion can occur within the container and the explosion can disperse radioactive materials into the surrounding environment. Accordingly, it is necessary to sample head gases which accumulate above the stored transuranic material in order to determine whether or not hazardous gases are being generated and if the vent filters are performing satisfactorily to let the gases escape.
The prior art approach has been to sample head space gas prior to installing the vent filter by sampling directly through a vent hole in the lid of a container. If it was necessary to sample head space gas after installation of the vent hole filter, the vent hole filter needed to be removed prior to sampling. This of course discourages sampling of head space gas because rather complex procedures must be followed in order to remove vent hole filters when a container contains hazardous waste such as transuranic waste or hazardous materials such as titanium oxides and salts. This of course discourages taking bead gas samples when perhaps the safest approach would be to take those samples in order to have a more reliable monitoring program.
In view of the aforementioned considerations, it is a feature of the present invention to incorporate a sampling facility with a vent filter in order to facilitate and make less complex sampling of materials in the containers.
In view of this feature and other features, the present invention is directed to an arrangement for sampling head space gas in a container having materials therein which include or generate gas accumulated in a head space above the materials. The arrangement comprises a vent insert having a filter element therein, the vent insert being disposed of a housing, the housing having a second portion which does not include the filter element. A bore through the second portion of the housing is adapted to receive a probe therethrough for withdrawing a sample of head space gas. Me bore contains a seal for sealing around the probe when the probe is inserted.
In more specific aspects of the invention, the seal is an elastic deformable material which allows the probe to be thrust therethrough and reseals behind the probe as the probe is withdrawn and the bore includes threads for receiving a threaded closure so as to impenetrably close the bore.
In still other aspects of the invention, the bore is coaxial with the axis of the vent if the filter element is annular and defines a hollow core through which the bore extends. In still other aspects of the invention, the bore is disposed obliquely with respect to the axis of the vent at an angle which does not intersect with the filter element whereby the probe may be inserted to pass beside the filter element into the head space.